Saturday, September 02, 2006

Twisted News item for students of bacterial cells: How transport proteins work.

A structure an ABC family transport protein that exports dyes and drugs from Staphylococcus aureus has just been reported in the journal Nature. The key discovery is that the two protein dimers in the molecule are intimately twistedaround each other. The structure provides many important clues on how the transport mechanism is driven by ATP hyrdrolysis.

Structure of a bacterial multidrug ABC transporter

Roger J. P. Dawson and Kaspar P. LocherAbstract

Multidrug transporters of the ABC family facilitate the export of diverse cytotoxic drugs across cell membranes. This is clinically relevant, as tumour cells may become resistant to agents used in chemotherapy. To understand the molecular basis of this process, we have determined the 3.0 Å crystal structure of a bacterial ABC transporter (Sav1866) from Staphylococcus aureus. The homodimeric protein consists of 12 transmembrane helices in an arrangement that is consistent with cross-linking studies and electron microscopic imaging of the human multidrug resistance protein MDR1, but critically different from that reported for the bacterial lipid flippase MsbA. The observed, outward-facing conformation reflects the ATP-bound state, with the two nucleotide-binding domains in close contact and the two transmembrane domains forming a central cavity—presumably the drug translocation pathway—that is shielded from the inner leaflet of the lipid bilayer and from the cytoplasm, but exposed to the outer leaflet and the extracellular space.

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About Me

Interested in correcting misuse of biology, helping people benefit from innovation.I teach courses in food science, food safety, biotechnology and microbiology at the University of Melbourne. My Bachelor Degree is in biochemistry and my Ph.D. applied molecular genetics. Thesis topic -- production of an animal feed supplement using genetically manipulated bacteria.---My recent publications have been on epidemics caused by bacterial pathogens, published in high-ranking journals. My current area of research is food risk analysis and management. The most important of these risks are microbes in food and microbial products that are toxic.